Magneto with protective mechanisms



Aug. 19, 1941.

W. E. SCHWARZMANN ETAL MAGNETO WITH PROTECTIVE MECHANISMS Filed Dec. 7,1940 0 E WEE? BY Java/1;:

A Qua.

AT'TORN EY Patented Aug. 19, 194i UNITED STATES PATENT OFFICE.

- 2,253,201 v MAGNETO wrrn rao'rso'nvn mscrmmsms Wolfgang E. Schwanmann,Longmeadow, and Charles Strniste, Agawam, Masa, assignors to AmericanBosch Corporation, Mass., a corporation of New York Springfield,

Application December '1, 1940, Serial No. 369,028 12-Claims. (Cl.171-209) The present invention relates to magnetos with protectivemechanisms normally arranged for electric spark ignition in internalcombustion engines, and it relates particularly to magnetos withpermanently connected generating windings,

and with'disabling circuits of the kind which automatically rendersthemagneto electrically incapable of generating ignition voltages uponremoval of a part normally fastened to the magneto and whichmaintainssuch inoperative condition of the magneto until the removable part isrestored to normal position.

It has happened after removing the cable connector of themanually-operative grounding switch from themagneto on an airplane, forpurposes of inspection or repair, that the connector was inadvertentlynot replaced in position, whereupon closure of the switch to presumablyprevent ignition while turning the propeller by hand, resulted fatallywhen the engine started into operation unexpectedly. The primary objector this invention is to provide for magnetos automatic protectivemechanism therefor, including any removable part whether for amanuallyoperative grounding switch or some other elec- .trical device asa vibrator for starting ignition or some mechanical device or membergenerally as a shield or cover, to prevent that or other unex-,

pected occurrence by automatically rendering the magneto electricallyincapable oi! generating ignition voltages upon removal of the part andfor maintaining the magneto in that inoperative con-- ment inapplication to an electrical device, not

only does the cable connector, when removed, permit the springto-automatically short circuit the circuit interrupter of the magneto,but, when restored to position on the magneto, it acts to electricallyconnect the live terminal of the circult interruptertothe electricaldevice. I e Other objects will appear iromtheviollowing descriptiontaken in connection withthe accompanying drawing showing magnetos withproteceach arranged, tor example, to short circuit the circuitinterrupter of the magtive mech neto by releasing a biased spring intoengagement with the grounded interrupter housing upon re'-,

moval of an'electrical connector or other part normally fastened to thehousing. In the draw- Fig. 1 shows, partly in section, and partlydiagrammatically, a plan view of a multicylinder high tension magnetohaving a manually-operative grounding switch; Fig. 2 similarly showsanother form of the protective mechanism applied generally to a magnetoand arranged for association with any electrical device in accordancewith the invention; and Fig. 3 shows a magneto with a removable partassociated with the cover of the interrupter housing.

Referring to theembodiment of Fig. 1, the magneto generally indicated bythe reference numeral I has permanently. connected. primary andsecondary generating windings 2 and 3, respectively, and a housing 4fo'rythe circuitinterrupting mechanism arranged in the, circuitot theprimary winding, all of well known construction and arrangement. Theinterrupter-mechanism includes a circuit interrupter having a pivoted 2spring-biased intermediate lever 5 periodically operated by the lobes ofcam 6 fast on shaft I of the rotor of the magneto. Upon eachsuch;

operation, the lever B engages the deflectable spring lever 8 andseparates its interrupter coritact 9 from the cooperative interruptercontact I III which ismounted on the bent-up portion H 1 of plate memberI! adiustablymounted on the interrupter disc I3. This disc ismechanically secured in adjustably timed position and electricallyconnected to the grounded housing I.

I and ,the lever 8 is supported from the terminal generally indicated byII, which being electrically insulated from disc II, as will-bedescribed more fully hereinafter in connection with Fig. 2, 40 forms thenormally live terminal of the circuit interrupter. The condenser i5 isconnected by the conductors l6, l1 between disc II and terminal H toelectrically shunt the interrupter contacts Q, It. The live terminal I4is connected by wire II to oneend of primary winding 2 and one end ofsecondary winding 3, the other end of the primary winding being groundedat I! and the other end of the secondary winding being con nectedto thedistributor rotor 20 for sequential distribution of the ignitionvoltages, generated by the magneto upon separation oi-the contacts I,"ll,,to the insulated electrodes ofthe grounded sparkplugs II in thewell known manner.

to thelive terminal ll of the interrupter is a conducting support 122,and also connected to this terminal and arranged around this support isa flat spring 23 which is biased toward engagement with the groundedhousing 4 as indicated by the broken lines, in which grounded positionthe normally live terminal 44 is grounded and renders the magnetoelectrically incapable of generating ignition voltages upon periodicseparation of the contacts 9, l0. However, the coil spring 24, which isstrong enough to overcome the spring 23, and which is secured at itsinner end to metal terminal 25 of the removable connector 26, holds thespring 23 in. its normally operative position shown in full lines out ofgrounding engagement whenever the connector is in place in the housing4, but upon removal of the connector from the housing permits the spring23 to move automatically into grounding position and to maintain thatgrounded position as long as the connector is removed. This terminal 25of connector 26 is electrically insulated from the housing asillustrated and s electrically connected in any suitable way to thecentral conductor 21 of the insulated and shielded cable 28. This cableis eelctrically'connected to the manually-operative grounding switch 29of the magneto and is held firmly in th connector by the rubber grommet30 which is compressed bythe nut 3| releasably locked in position by thespring fingers 32. The complete connector 26, with its spring 24 andterminal 25 and with the attached cable 23, is readily removable andreplaceable by screwing it out of and into engagement with the threadednipple 33 of the housing 7 4. Thus, with'the parts in normal position asshown in Fig. 1, the live terminal l4 of the in terrupter iselectrically connected to the grounding switch 29 which then may beoperated at will to ground the magneto-todepriv'e the engine of ignitionand, with the connector removed from a magneto installation on an engineto inspect or repair the magneto, connector or magneto grounding switchor for any other purpose, the interrupter is automatically andpermanently grounded on the housing 4 by the spring 23, as shown in Fig.1 in broken. lines, whether the magneto grounding switch 29 is closed oropen.

In the embodiment of Fig. 2, the interrupter housing 4' contains thesame or other suitable circuit interrupting mechanism and the wire I 8leading from the ignition coil of the magneto through an opening at 34in the disc l3 to the live terminal l4. As in the embodiment of Fig. 1.this terminal comprises an upstanding metal post 35 fastened to disc l3and insulated as indicated from the bolt 36 and nut 31. In this case,however, the automatic grounding spring is in the form of a closed loop38 having its ends, fastened and electrically connected to the liveterminal l4 and being biased toward engagement with the grounded housing4 as indicated in broken lines. Also in this case, the removableconnector 39 has a conducting terminal 4D which is insulated as shownfrom the metal nut 4| and the externally threaded nipple 42 butelectrically connected in any suitable way to the central wire 43 of thecable 44, and which in normal position of the connector on the housingholds the spring 38 in the position shown in full lines out of groundingengagement with the housing. The wire 43 may be connected to amanually-operativ magneto grounding switch as in Fig. 1 or to any otherelectrical device as a vibrator for supplying pulsating currents to theignition coil to start the engine into normal operation by a shower ofsparks in the well known manner. Thus, as in the embodiment of Fig. 1,when the connector 39 isin normal position as shown, the live terminall4 of the interrupter is electrically connected to the wire 43 and themagneto is in electrical condition to generate ignition voltages, butupon removalpf the connector the interrupter is automatically groundedby the spring 38 and the magneto remains electrically incapable of suchgeneration until the connector is replaced in normal position on thehousing.

In the embodiment of Fig. 3, the removable part is the cover 45 of theinterrupter housing 46. This cover has fastened to it a member 41 ofinsulating material which, when the cover is in normal position, overthe end of the housing as indicated, holds the spring 23 in the fullline position to render the magneto electrically operative, and which,when the cover is removed as for inspection of the interruptingmechanism, allows the spring to automatically assume its groundingposition in engagement with the housing 48, so as to render the magnetoelectrically incapable of generation and to maintain that inoperativecondition until the cover is replaced. If desired, a magneto groundingswitch of some suitable arrangement can be added to this embodiment tocut off the ignition at will.

It will be apparent that the electrical circuit containing the spring 23of Figs. 1 and 3 or the spring 38 of Fig. 2 constitutes for the magnetoin each case a disabling circuit including a switch comprising thegrounded interrupter housing as one pole and the engageable end of thespring as the other pole. Since, as shown in Fig, 1, the primary winding2, secondary winding 3 and interrupter lever 5 are each grounded on theinterrupter housing 4, this disabling circuit acts, when the springengages the housing upon removal of the removable member, to shortcircuit the generating winding and the interrupter.

The operation of the three embodiments specifically described herein,will be understood from the foregoing. As will be apparent to thoseskilled in the art, the magneto may be rendered incapable of generatingignition voltages upon removal of a part of the magneto, or a part of adevice or member associated with the magneto, by short circuiting theprimary circuit in the case of low tension and high tension magnetos, orat least a portion thereof as for instance the circuit interrupter, orby a portion at least of the high tension circuit in the case of hightension magnetos, by utilizing a grounded disabling circuit for th shortcircuiting arrangement in a magneto, not only is no partof anygenerating circuit disrupted to disable the magneto, but only one liveterminal of the circuit need be engaged. By short circuiting the lowtension winding, there is the additional advantage of operating upon alow tension connection, and by short circuiting the circuit interrupter,there is the further additional advantage of having a live terminalreadily available for the purpose and also of utilizing the terminalsuitable for connection to a magneto grounding switch or a startingvibrator or other electrical device. Also it Will be apparent that themagneto may be for engines of any number of cylinders and of the rotary,oscillating or other type, and also of the type in which generation ofignition voltages occurs upon closure of the circuit interrupter as wellas upon the opening thereof. Therefore, the terms of the appended claimsare intended to be interpreted in their broadest sense.

Having thus described the invention. what is claimed is: v

1. In combination, a magneto having a permanently connected circuitnormally operative to generate ignition voltages, a disabling circuitwhich is effective to render the magneto inoperative by rendering thegenerating circuit electrically incapable of such generation and whichincludes an automatic switch automatically opera- I tive to a positionto render the disabling circuit eifective, and a removable part normallyfastened to the magneto and having means which upon removal of the partfrom its normal position releases the switch for its automatic operationand which upon. restoring the part to its normal position automaticallyrenders the switch inoperative and thereafter keeps it inoperative,whereby removal of the part automatically renders the magnetoinoperative and maintains it in that inoperative condition until thepart is restored.

2. In combination, a magneto having a permanently connected circuitnormally operative to generate ignition voltage, a disabling circuitwhich is effective to render the magneto inoperative by rendering thegenerating circuit electrically in- 5. In combination, a magneto havinga high tension circuit and a permanently connected low tension circuitoperative to generate ignition voltages, a disabling circuit which iselective on the removal of the part from its normal position recapableof such generation and whichincludes an automatic switch automaticallyoperative when unrestrained to a position to-render the disablingcircuit effective, and a removable part normally fastened to the magnetoand having means which upon'removal of the part from its normal positionreleases the switch for its automatic operation and which upon restoringthe part to its normal position automatically opens the switch andthereafter holds it open, whereby removal of the part automaticallyrenders the magneto inoperative and maintains it in that inoperativecondition until the part, is restored.

3. In combination, a magneto having a permanently connected circuitnormally operative to generate ignition voltages, a disabling circuitwhich is effective to render the magneto inoperative by rendering thegenerating 'circuit electrically incapable of such generation. and whichincludes a spring biased toward a position to render the disablingcircuit eifective, and a removable part normally fastened to the magnetoand having meaiis which upon removal of the removable part from itsnormal position releases the spring for automatic operation to itseffective position and which upon restoring the part to its normalposition automatically moves the spring out of its effective positionand thereafter holds it out of such p0siti0n,-whereby the removal of theremovable part automatically renders the magneto inoperative andmaintains it in that inoperative condition until the removable part isrestored.

4. In combination, a magneto having a permanently connected circuitnormally operative to generate ignition voltages, a disabling circuitwhich shunts a portion at'least of the generating circuit to therebyrender the magneto inoperative by rendering the generating circuitincapable of such generation and which includes an automatic switchautomatically operative to render the disabling circuit effective, and aremovable part normally fastened to the magneto and having means whichupon removal of the part from its normal position releases the switchfor its automatic operation and which upon restoring the part to itsnormal position automatically renders the switch inoperative, wherebyremoval of the part automatically renders the magneto inoperative andmaintains it in that inoperative condition until the part is restored.

leases the switch for its automatic operation and which upon restoringthe part to its normal position automatically renders the switchinoperative and thereafter keeps it inoperative, whereby removal of -thepart automatically renders the magneto inoperative and maintains it inthat inoperative condition untilthe part is restored.

6. In combination; a magneto having a permanently connected circuitincluding a circuit interrupter normally operative to generate ignitionvoltages, a disabling circuit'which is effective to render the circuitinterrupter electrically inoperative and thereby render the generatingcircuit electrically incapable of such generation and which includes anautomatic switch automatically operative to afposition torender thedisabling circuit effective, and a removable part normally fastened tothe magneto and having means which upon removal of the part from itsnormal positionreleases the switch for its automatic operation and whichupon restoring the part to its normal position automatically renders theswitch inoperative and thereafter keeps it inoperative, whereby removalof the part automatically renders the magneto inoperative and maintainsit in. that inoperative condition until the part is restored.

'1. In combination, a magneto having a permanently connected groundedcircuit normally operative to generate ignition voltages, a disablingcircuit which is connected to a live ter-- minal of the generatingcircuit and is arranged to render the magneto inoperative by shuntingits generating circuit and which includes an automatic switchautomatically operative to engagement with a grounding part, and aremovable part normally fastened to the magneto and having means whichupon removal of the removable part from its normal position releases theswitch for its automatic operation and which upon restoring the part toits normal position automatically moves the switch from its groundingposition and thereafter holds it out of such position, whereby theremoval of the removable part auto,- matically renders the magnetoinoperative and maintains it in that inoperative condition until theremovable P rt is restored.

8. In combination, a magnetohaving a permanently connected circuitincluding a permanently grounded circuit interrupter normally operativeto generate ignition voltages, a disabling circuit which is connected toa live terminal of the circuit interrupter and is arranged to render themagneto inoperative by shunting the circuit interrupter and whichincludes an automatic switch automatically operative to engagement witha grounding part, and a removable part normally fastened to the magnetoand having means which upon removal of the removable part from itsnormal position releases the switch for its automatic operation andwhich upon restoring the part to its normal position automatically movesthe switch from its grounding position and thereafter holds it out ofsuch position, whereby the removal the removable part automaticallyrenders the magneto inoperative and maintains it in that inoperativecondition until the removable part is restored.

9. In combination, a magneto having a permanently connected circuitincluding a circuit interrupter mounted in and electrically connected toan interrupter housing and normally operative to generate ignitionvoltages, a disabling circuit which is effective to render the magnetoinoperative by rendering the generating circuit electrically incapableof such generation and which includes a spring fastened to a terminal ofthe circuit interrupter and biased toward engagement with the housing,and a removable part normally fastened to the housing and having meanswhich upon removal of the part from its normal position releases thespring for its automatic operation and which upon restoring the part toits normal position automatically moves the spring out of engagementwith the housing and thereafter holds it in that position, whereby theremoval of the removable part automatically renders the magnetoinoperative and maintains it in that inoperative condition until theremovable part is restored.

10. In combination, a magneto having a permanently connected circuitnormally operative to generate ignition voltages, an electrical deviceassociated with the magneto and having a connector removably fastened tothe magneto, and a disabling circuit which is effective to render themagneto inoperative by rendering the generating circuit electricallyincapable of such generation and which includes an automatic switchautomatically operative to a position to render the disabling circuiteffective, the connector having means which upon removal of theconnector from the magneto releases the switch for its automaticoperation and which upon restoring the connector to the magnetoautomatically renders the switch inoperative and thereafter keeps itinoperative, the connector also having means for electrically connectingthe electrical device to the generating winding when the connector isfastened to the magneto.

11. In combination, a magneto having a permanently connected circuitincluding a circuit interrupter grounded in an interrupter housing andnormally operative to generate ignition voltages, a disabling circuitwhich is effective to render the magneto inoperative by rendering thegenerating circuit electrically incapable of such generation and whichincludes a spring connected to a live terminal of the circuitinterrupter and biased toward engagement with the housing, and anelectrical device associated with the magneto and having a connectorremovably fastened to the interrupter housing, the connector having aconductor which when the connector is fastened to the housing holds thespring out of engagement with the housing and electrically connects thespring to the electrical device and which when, the connector is removedfrom the housing releases the spring for its automatic operation.

12. In combination, a magneto having a permanently connected circuitnormally operative to generate ignition voltages, a disabling circuitwhich is effective to render the magneto inoperative by rendering thegenerating circuit'electrically incapable of such generation and whichincludes an automatic switch automatically operative to a position torender the disabling circuit effective, and a removable mechanical partof the magneto having means which upon removal of the part from themagneto releases the switch for its automatic operation and which uponrestoring the part to its normal position automatically renders theswitch inoperative and thereafter keeps it inoperative, whereby removalof the removable part automatically renders the magneto inoperative andmaintains it in that inoperative condition until the part is restored.

WOLFGANG E. SCHWARZMANN. CHARLES STRNIS'I'E.

